[PATCH] nvme: fix hang in remove path

[Rakesh Pandit]

On Tue, Jun 06, 2017 at 09:12:23AM +0200, Christoph Hellwig wrote:
> On Tue, Jun 06, 2017 at 10:10:45AM +0300, Sagi Grimberg wrote:
> >
> >>>> Note 7 here is NVME_SC_ABORT_REQ.  Also we would avoid walking through
> >>>> all power states inside the nvme_configure_apst as
> >>>> nvme_set_latency_tolerance was called with value
> >>>> PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT (-1) which sets
> >>>> ctrl->ps_max_latency_us to U64_MAX and tries to send a sync command
> >>>> which of course fails with error message.
> >>
> >> Even though this change from this patch does fix the hang, just tested
> >> again and I can see above error message "failed to set APST feature 7"
> >> while nvme_remove PID is getting executed.
> >>
> >> So, sync requests (while nvme_remove is executing) are going through
> >> and not everything is handled well in .queue_rq while controller is
> >> under deleting state or dead state.
> >
> > The error message is expected because queue_rq is failing the I/O, did
> > you see it actually hang?

No hang.

> >
> > Personally I'm not too bothered with the error log, we can suppress it
> > conditional on the ctrl state if it really annoys people, but if we're
> > conditioning on the ctrl state, we can do it like you suggested anyway...
> 
> Yeah.  Or just remove the error printk entirely..

Thanks for input, lets ignore.

Based on earlier message I guess this is already queued.  If not it
seems worth adding for 4.12-rc.